'Abdullah bin Busr (May Allah be pleased with him) reported:
One of the Companions said, "O Messenger of Allah. There are many injunctions of Islam for me. So tell me something to which I may hold fast." He said, "Keep your tongue wet with the remembrance of Allah."[At-Tirmidhi].
App reference: Book 16, Hadith 31
Arabic/English book reference: Book 16, Hadith 1438